deps: Upgrade intl constraint, from ^0.18.0 to ^0.19.0

No potentially breaking changes identified in the changelog:
  https://github.com/dart-lang/i18n/blob/main/pkgs/intl/CHANGELOG.md#0190

This addresses the following error:

  Note: intl is pinned to version 0.19.0 by flutter_localizations
    from the flutter SDK.
  See https://dart.dev/go/sdk-version-pinning for details.

  Because zulip depends on flutter_localizations from sdk which
    depends on intl 0.19.0, intl 0.19.0 is required.
  So, because zulip depends on intl ^0.18.0, version solving failed.

  You can try the following suggestion to make the pubspec resolve:
  * Try upgrading your constraint on intl:
    flutter pub add intl:^0.19.0

pubspec.lock

@@ -616,10 +616,10 @@ packages:
     dependency: "direct main"
     description:
       name: intl
-      sha256: "3bc132a9dbce73a7e4a21a17d06e1878839ffbf975568bc875c60537824b0c4d"
+      sha256: d6f56758b7d3014a48af9701c085700aac781a92a87a62b1333b46d8879661cf
       url: "https://pub.dev"
     source: hosted
-    version: "0.18.1"
+    version: "0.19.0"
   io:
     dependency: transitive
     description:
@@ -1197,10 +1197,10 @@ packages:
     dependency: transitive
     description:
       name: vm_service
-      sha256: a2662fb1f114f4296cf3f5a50786a2d888268d7776cf681aa17d660ffa23b246
+      sha256: e7d5ecd604e499358c5fe35ee828c0298a320d54455e791e9dcf73486bc8d9f0
       url: "https://pub.dev"
     source: hosted
-    version: "14.0.0"
+    version: "14.1.0"
   watcher:
     dependency: transitive
     description:

pubspec.yaml

@@ -54,7 +54,7 @@ dependencies:
   html: ^0.15.1
   http: ^1.0.0
   image_picker: ^1.0.0
-  intl: ^0.18.0
+  intl: ^0.19.0
   json_annotation: ^4.8.1
   package_info_plus: ^5.0.1
   path: ^1.8.3